From patchwork Thu Aug 22 19:33:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev\" via" X-Patchwork-Id: 11110151 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 15023184E for ; Thu, 22 Aug 2019 21:58:05 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CF9A020679 for ; Thu, 22 Aug 2019 21:58:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="K7rwguaQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF9A020679 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:48116 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0v5n-0005fY-Tg for patchwork-qemu-devel@patchwork.kernel.org; Thu, 22 Aug 2019 17:58:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42870) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20@lizzy.crudebyte.com>) id 1i0v50-0004JV-Ei for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:57:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20@lizzy.crudebyte.com>) id 1i0v4x-0006Hu-Nu for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:57:14 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:33343) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20@lizzy.crudebyte.com>) id 1i0v4x-000623-7A for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:57:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Subject:Date:Cc:To:From:References:In-Reply-To: Message-Id:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=vnME3I052jcZIHUVQ8d2TkPqHGmKWQEf9VDFkZhhJiE=; b=K7rwguaQbrOA6IwW606m2RoLk CJQEgJj50BX1lhwP1YFQfwvAjK0Xh2vXXEZvYo6qfNAAGiie50bnwA4igzwxHNMcvOh5qmfAyWdD5 lJh4uxVqZfikMgYt22h1fWIWD/igkBgNZ5pzHMlvGB2jA6aptVB5pVlAEjJIKd+walRFYzuF9ATJY Y4Txl61PHjwwWqTv6lwIuZmwwRllThHlIpPDsDvgQXpEzRDs4WPu/izPaB+7AE1SzX6Afi8mjJm+d vHctLi2sGa1xJF89s8vkGZB3wZfJ4bxPVYd1pF09pBJZmEqPe7yjVzz63irLMBSoMDGQ2b+CDu7+R KDj5huBxg==; Message-Id: <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20.1566503584.git.qemu_oss@crudebyte.com> In-Reply-To: References: To: qemu-devel@nongnu.org Date: Thu, 22 Aug 2019 21:33:37 +0200 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 91.194.90.13 Subject: [Qemu-devel] [PATCH v6 2/4] 9p: Added virtfs option 'multidevs=remap|forbid|warn' X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Christian Schoenebeck via Qemu-devel From: "Denis V. Lunev\" via" Reply-To: Christian Schoenebeck Cc: Stefan Hajnoczi , Daniel =?utf-8?b?UC4gQmVycmFuZ8Op?= , Greg Kurz , Antonios Motakis , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" 'warn' (default): Only log an error message (once) on host if more than one device is shared by same export, except of that just ignore this config error though. This is the default behaviour for not breaking existing installations implying that they really know what they are doing. 'forbid': Like 'warn', but except of just logging an error this also denies access of guest to additional devices. 'remap': Allows to share more than one device per export by remapping inodes from host to guest appropriately. To support multiple devices on the 9p share, and avoid qid path collisions we take the device id as input to generate a unique QID path. The lowest 48 bits of the path will be set equal to the file inode, and the top bits will be uniquely assigned based on the top 16 bits of the inode and the device id. Signed-off-by: Antonios Motakis [CS: - Rebased to https://github.com/gkurz/qemu/commits/9p-next (SHA1 177fd3b6a8). - Updated hash calls to new xxhash API. - Added virtfs option 'multidevs', original patch simply did the inode remapping without being asked. - Updated docs for new option 'multidevs'. - Capture root_ino in v9fs_device_realize_common() as well, not just the device id. - Fixed v9fs_do_readdir() not having remapped inodes. - Log error message when running out of prefixes in qid_path_prefixmap(). - Fixed definition of QPATH_INO_MASK. - Dropped unnecessary parantheses in qpp_lookup_func(). - Dropped unnecessary g_malloc0() result checks. ] Signed-off-by: Christian Schoenebeck --- fsdev/file-op-9p.h | 5 ++ fsdev/qemu-fsdev-opts.c | 7 +- fsdev/qemu-fsdev.c | 11 +++ hw/9pfs/9p.c | 182 ++++++++++++++++++++++++++++++++++++++++++------ hw/9pfs/9p.h | 13 ++++ qemu-options.hx | 33 +++++++-- vl.c | 6 +- 7 files changed, 229 insertions(+), 28 deletions(-) diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h index c757c8099f..f2f7772c86 100644 --- a/fsdev/file-op-9p.h +++ b/fsdev/file-op-9p.h @@ -59,6 +59,11 @@ typedef struct ExtendedOps { #define V9FS_RDONLY 0x00000040 #define V9FS_PROXY_SOCK_FD 0x00000080 #define V9FS_PROXY_SOCK_NAME 0x00000100 +/* + * multidevs option (either one of the two applies exclusively) + */ +#define V9FS_REMAP_INODES 0x00000200 +#define V9FS_FORBID_MULTIDEVS 0x00000400 #define V9FS_SEC_MASK 0x0000003C diff --git a/fsdev/qemu-fsdev-opts.c b/fsdev/qemu-fsdev-opts.c index 7c31ffffaf..07a18c6e48 100644 --- a/fsdev/qemu-fsdev-opts.c +++ b/fsdev/qemu-fsdev-opts.c @@ -31,7 +31,9 @@ static QemuOptsList qemu_fsdev_opts = { }, { .name = "readonly", .type = QEMU_OPT_BOOL, - + }, { + .name = "multidevs", + .type = QEMU_OPT_STRING, }, { .name = "socket", .type = QEMU_OPT_STRING, @@ -76,6 +78,9 @@ static QemuOptsList qemu_virtfs_opts = { .name = "readonly", .type = QEMU_OPT_BOOL, }, { + .name = "multidevs", + .type = QEMU_OPT_STRING, + }, { .name = "socket", .type = QEMU_OPT_STRING, }, { diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c index 077a8c4e2b..ed03d559a9 100644 --- a/fsdev/qemu-fsdev.c +++ b/fsdev/qemu-fsdev.c @@ -58,6 +58,7 @@ static FsDriverTable FsDrivers[] = { "writeout", "fmode", "dmode", + "multidevs", "throttling.bps-total", "throttling.bps-read", "throttling.bps-write", @@ -121,6 +122,7 @@ int qemu_fsdev_add(QemuOpts *opts, Error **errp) const char *fsdev_id = qemu_opts_id(opts); const char *fsdriver = qemu_opt_get(opts, "fsdriver"); const char *writeout = qemu_opt_get(opts, "writeout"); + const char *multidevs = qemu_opt_get(opts, "multidevs"); bool ro = qemu_opt_get_bool(opts, "readonly", 0); if (!fsdev_id) { @@ -161,6 +163,15 @@ int qemu_fsdev_add(QemuOpts *opts, Error **errp) } else { fsle->fse.export_flags &= ~V9FS_RDONLY; } + if (multidevs) { + if (!strcmp(multidevs, "remap")) { + fsle->fse.export_flags &= ~V9FS_FORBID_MULTIDEVS; + fsle->fse.export_flags |= V9FS_REMAP_INODES; + } else if (!strcmp(multidevs, "forbid")) { + fsle->fse.export_flags &= ~V9FS_REMAP_INODES; + fsle->fse.export_flags |= V9FS_FORBID_MULTIDEVS; + } + } if (fsle->fse.ops->parse_opts) { if (fsle->fse.ops->parse_opts(opts, &fsle->fse, errp)) { diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 8cc65c2c67..c96ea51116 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -25,6 +25,7 @@ #include "trace.h" #include "migration/blocker.h" #include "sysemu/qtest.h" +#include "qemu/xxhash.h" int open_fd_hw; int total_open_fd; @@ -571,22 +572,109 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu) P9_STAT_MODE_NAMED_PIPE | \ P9_STAT_MODE_SOCKET) -/* This is the algorithm from ufs in spfs */ + +/* creative abuse of tb_hash_func7, which is based on xxhash */ +static uint32_t qpp_hash(QppEntry e) +{ + return qemu_xxhash7(e.ino_prefix, e.dev, 0, 0, 0); +} + +static bool qpp_lookup_func(const void *obj, const void *userp) +{ + const QppEntry *e1 = obj, *e2 = userp; + return e1->dev == e2->dev && e1->ino_prefix == e2->ino_prefix; +} + +static void qpp_table_remove(void *p, uint32_t h, void *up) +{ + g_free(p); +} + +static void qpp_table_destroy(struct qht *ht) +{ + qht_iter(ht, qpp_table_remove, NULL); + qht_destroy(ht); +} + +/* stat_to_qid needs to map inode number (64 bits) and device id (32 bits) + * to a unique QID path (64 bits). To avoid having to map and keep track + * of up to 2^64 objects, we map only the 16 highest bits of the inode plus + * the device id to the 16 highest bits of the QID path. The 48 lowest bits + * of the QID path equal to the lowest bits of the inode number. + * + * This takes advantage of the fact that inode number are usually not + * random but allocated sequentially, so we have fewer items to keep + * track of. + */ +static int qid_path_prefixmap(V9fsPDU *pdu, const struct stat *stbuf, + uint64_t *path) +{ + QppEntry lookup = { + .dev = stbuf->st_dev, + .ino_prefix = (uint16_t) (stbuf->st_ino >> 48) + }, *val; + uint32_t hash = qpp_hash(lookup); + + val = qht_lookup(&pdu->s->qpp_table, &lookup, hash); + + if (!val) { + if (pdu->s->qp_prefix_next == 0) { + /* we ran out of prefixes */ + error_report_once( + "9p: No more prefixes available for remapping inodes from " + "host to guest." + ); + return -ENFILE; + } + + val = g_malloc0(sizeof(QppEntry)); + *val = lookup; + + /* new unique inode prefix and device combo */ + val->qp_prefix = pdu->s->qp_prefix_next++; + qht_insert(&pdu->s->qpp_table, val, hash, NULL); + } + + *path = ((uint64_t)val->qp_prefix << 48) | (stbuf->st_ino & QPATH_INO_MASK); + return 0; +} + static int stat_to_qid(V9fsPDU *pdu, const struct stat *stbuf, V9fsQID *qidp) { + int err; size_t size; - if (pdu->s->dev_id != stbuf->st_dev) { - error_report_once( - "9p: Multiple devices detected in same VirtFS export. " - "You must use a separate export for each device." - ); - return -ENODEV; + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { + /* map inode+device to qid path (fast path) */ + err = qid_path_prefixmap(pdu, stbuf, &qidp->path); + if (err) { + return err; + } + } else { + if (pdu->s->dev_id != stbuf->st_dev) { + if (pdu->s->ctx.export_flags & V9FS_FORBID_MULTIDEVS) { + error_report_once( + "9p: Multiple devices detected in same VirtFS export. " + "Access of guest to additional devices is (partly) " + "denied due to virtfs option 'multidevs=forbid' being " + "effective." + ); + return -ENODEV; + } else { + error_report_once( + "9p: Multiple devices detected in same VirtFS export, " + "which might lead to file ID collisions and severe " + "misbehaviours on guest! You should either use a " + "separate export for each device shared from host or " + "use virtfs option 'multidevs=remap'!" + ); + } + } + memset(&qidp->path, 0, sizeof(qidp->path)); + size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); + memcpy(&qidp->path, &stbuf->st_ino, size); } - memset(&qidp->path, 0, sizeof(qidp->path)); - size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); - memcpy(&qidp->path, &stbuf->st_ino, size); qidp->version = stbuf->st_mtime ^ (stbuf->st_size << 8); qidp->type = 0; if (S_ISDIR(stbuf->st_mode)) { @@ -616,6 +704,30 @@ static int coroutine_fn fid_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, return 0; } +static int coroutine_fn dirent_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, + struct dirent *dent, V9fsQID *qidp) +{ + struct stat stbuf; + V9fsPath path; + int err; + + v9fs_path_init(&path); + + err = v9fs_co_name_to_path(pdu, &fidp->path, dent->d_name, &path); + if (err < 0) { + goto out; + } + err = v9fs_co_lstat(pdu, &path, &stbuf); + if (err < 0) { + goto out; + } + err = stat_to_qid(pdu, &stbuf, qidp); + +out: + v9fs_path_free(&path); + return err; +} + V9fsPDU *pdu_alloc(V9fsState *s) { V9fsPDU *pdu = NULL; @@ -1964,16 +2076,39 @@ static int coroutine_fn v9fs_do_readdir(V9fsPDU *pdu, V9fsFidState *fidp, v9fs_string_free(&name); return count; } - /* - * Fill up just the path field of qid because the client uses - * only that. To fill the entire qid structure we will have - * to stat each dirent found, which is expensive - */ - size = MIN(sizeof(dent->d_ino), sizeof(qid.path)); - memcpy(&qid.path, &dent->d_ino, size); - /* Fill the other fields with dummy values */ - qid.type = 0; - qid.version = 0; + + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { + /* + * dirent_to_qid() implies expensive stat call for each entry, + * we must do that here though since inode remapping requires + * the device id, which in turn might be different for + * different entries; we cannot make any assumption to avoid + * that here. + */ + err = dirent_to_qid(pdu, fidp, dent, &qid); + if (err < 0) { + v9fs_readdir_unlock(&fidp->fs.dir); + v9fs_co_seekdir(pdu, fidp, saved_dir_pos); + v9fs_string_free(&name); + return err; + } + } else { + /* + * Fill up just the path field of qid because the client uses + * only that. To fill the entire qid structure we will have + * to stat each dirent found, which is expensive. For the + * latter reason we don't call dirent_to_qid() here. Only drawback + * is that no multi-device export detection of stat_to_qid() + * would be done and provided as error to the user here. But + * user would get that error anyway when accessing those + * files/dirs through other ways. + */ + size = MIN(sizeof(dent->d_ino), sizeof(qid.path)); + memcpy(&qid.path, &dent->d_ino, size); + /* Fill the other fields with dummy values */ + qid.type = 0; + qid.version = 0; + } /* 11 = 7 + 4 (7 = start offset, 4 = space for storing count) */ len = pdu_marshal(pdu, 11 + count, "Qqbs", @@ -3672,8 +3807,13 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, goto out; } + s->root_ino = stat.st_ino; s->dev_id = stat.st_dev; + /* QID path hash table. 1 entry ought to be enough for anybody ;) */ + qht_init(&s->qpp_table, qpp_lookup_func, 1, QHT_MODE_AUTO_RESIZE); + s->qp_prefix_next = 1; /* reserve 0 to detect overflow */ + s->ctx.fst = &fse->fst; fsdev_throttle_init(s->ctx.fst); @@ -3687,6 +3827,7 @@ out: } g_free(s->tag); g_free(s->ctx.fs_root); + qpp_table_destroy(&s->qpp_table); v9fs_path_free(&path); } return rc; @@ -3699,6 +3840,7 @@ void v9fs_device_unrealize_common(V9fsState *s, Error **errp) } fsdev_throttle_cleanup(s->ctx.fst); g_free(s->tag); + qpp_table_destroy(&s->qpp_table); g_free(s->ctx.fs_root); } diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index 5e316178d5..a283b0193e 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -8,6 +8,7 @@ #include "fsdev/9p-iov-marshal.h" #include "qemu/thread.h" #include "qemu/coroutine.h" +#include "qemu/qht.h" enum { P9_TLERROR = 6, @@ -235,6 +236,15 @@ struct V9fsFidState V9fsFidState *rclm_lst; }; +#define QPATH_INO_MASK ((1ULL << 48) - 1) + +/* QID path prefix entry, see stat_to_qid */ +typedef struct { + dev_t dev; + uint16_t ino_prefix; + uint16_t qp_prefix; +} QppEntry; + struct V9fsState { QLIST_HEAD(, V9fsPDU) free_list; @@ -256,7 +266,10 @@ struct V9fsState Error *migration_blocker; V9fsConf fsconf; V9fsQID root_qid; + ino_t root_ino; dev_t dev_id; + struct qht qpp_table; + uint16_t qp_prefix_next; }; /* 9p2000.L open flags */ diff --git a/qemu-options.hx b/qemu-options.hx index 9621e934c0..603e5e8e15 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1335,17 +1335,17 @@ ETEXI DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n" - " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode]\n" - "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly]\n" - "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly]\n" + " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n" + "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly][,multidevs=remap|forbid|warn]\n" + "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly][,multidevs=remap|forbid|warn]\n" "-virtfs synth,mount_tag=tag[,id=id][,readonly]\n", QEMU_ARCH_ALL) STEXI -@item -virtfs local,path=@var{path},mount_tag=@var{mount_tag} ,security_model=@var{security_model}[,writeout=@var{writeout}][,readonly] [,fmode=@var{fmode}][,dmode=@var{dmode}] -@itemx -virtfs proxy,socket=@var{socket},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly] -@itemx -virtfs proxy,sock_fd=@var{sock_fd},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly] +@item -virtfs local,path=@var{path},mount_tag=@var{mount_tag} ,security_model=@var{security_model}[,writeout=@var{writeout}][,readonly] [,fmode=@var{fmode}][,dmode=@var{dmode}][,multidevs=@var{multidevs}] +@itemx -virtfs proxy,socket=@var{socket},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly][,multidevs=@var{multidevs}] +@itemx -virtfs proxy,sock_fd=@var{sock_fd},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly][,multidevs=@var{multidevs}] @itemx -virtfs synth,mount_tag=@var{mount_tag} @findex -virtfs @@ -1399,6 +1399,27 @@ Specifies the default mode for newly created directories on the host. Works only with security models "mapped-xattr" and "mapped-file". @item mount_tag=@var{mount_tag} Specifies the tag name to be used by the guest to mount this export point. +@item multidevs=@var{multidevs} +Specifies how to deal with multiple devices being shared with a 9p export. +Supported behaviours are either "remap", "forbid" or "warn". The latter is +the default behaviour on which virtfs 9p expects only one device to be +shared with the same export, and if more than one device is shared and +accessed via the same 9p export then only a warning message is logged +(once) by qemu on host side. In order to avoid file ID collisions on guest +you should either create a separate virtfs export for each device to be +shared with guests (recommended way) or you might use "remap" instead which +allows you to share multiple devices with only one export instead, which is +achieved by remapping the original inode numbers from host to guest in a +way that would prevent such collisions. Remapping inodes in such use cases +is required because the original device IDs from host are never passed and +exposed on guest. Instead all files of an export shared with virtfs always +share the same device id on guest. So two files with identical inode +numbers but from actually different devices on host would otherwise cause a +file ID collision and hence potential misbehaviours on guest. "forbid" on +the other hand assumes like "warn" that only one device is shared by the +same export, however it will not only log a warning message but also +deny access to additional devices on guest. Note though that "forbid" does +currently not block all possible file access operations. @end table ETEXI diff --git a/vl.c b/vl.c index b426b32134..9cb29b483d 100644 --- a/vl.c +++ b/vl.c @@ -3320,7 +3320,7 @@ int main(int argc, char **argv, char **envp) case QEMU_OPTION_virtfs: { QemuOpts *fsdev; QemuOpts *device; - const char *writeout, *sock_fd, *socket, *path, *security_model; + const char *writeout, *sock_fd, *socket, *path, *security_model, *multidevs; olist = qemu_find_opts("virtfs"); if (!olist) { @@ -3380,6 +3380,10 @@ int main(int argc, char **argv, char **envp) qemu_opt_set_bool(fsdev, "readonly", qemu_opt_get_bool(opts, "readonly", 0), &error_abort); + multidevs = qemu_opt_get(opts, "multidevs"); + if (multidevs) { + qemu_opt_set(fsdev, "multidevs", multidevs, &error_abort); + } device = qemu_opts_create(qemu_find_opts("device"), NULL, 0, &error_abort); qemu_opt_set(device, "driver", "virtio-9p-pci", &error_abort);